y=(square root of x3)
y=(square root of 2x+5)7
f(x)=(square root of 9+x)
please help? Thanks.
y=(square root of 2x+5)7
f(x)=(square root of 9+x)
please help? Thanks.

ok so the square root of something can't be negative. So the thing under the radical has to be positive or zero. For the first one, x is all real numbers greater than or equal to 3. For the second one, x is all real numbers greater than or equal to 2.5. For the third one, x is all real number greater than or equal to 9.

y=(square root of x3) = (x3)^1/2 >>>>> domain is [ 3 , infinity)
y=(square root of 2x+5)7 = (2x+5)^1/2 7 >>>> 2x+5 >= 0 , x >= 5/2 ////domain= [ 5/2 , infinity )
f(x)=(square root of 9+x) = (9+x)^1/2 >>>> 9+x >= 0 , x >= 9 /////domain = [ 9 , infinity)
y=(square root of 2x+5)7 = (2x+5)^1/2 7 >>>> 2x+5 >= 0 , x >= 5/2 ////domain= [ 5/2 , infinity )
f(x)=(square root of 9+x) = (9+x)^1/2 >>>> 9+x >= 0 , x >= 9 /////domain = [ 9 , infinity)